The European Union's executive arm Wednesday proposed sweeping changes to the way the bloc supervises its financial markets, a plan that could face fierce resistance from some EU states.

The European Commission's proposal will create two umbrella groups aimed at unifying the EU's patchwork of national rules and overseers.

One group, incorporating the bloc's central bankers and national financial market supervisors, will look at big-picture risks and try to issue early warnings.

The other body will bring together national supervisors and three new bloc-wide regulators focused on securities, banking and the insurance and pensions sectors. This group will ensure countries uniformly follow the EU's rules, coordinate responses to emergencies like bank failures and mediate in disputes between national authorities.

This proposal "will go a long way towards tackling the imbalances in our financial systems and solving the weaknesses in our financial supervision system that are at least partly to blame for the financial crisis," European Commissioner for Economic and Monetary Affairs Joaquin Almunia said in a statement.

These plans could rankle the UK and other countries that don't want to give up sway over their own financial markets. London is the EU's largest and most lucrative financial center and UK officials in recent months have resisted pressure for more centralised EU powers.

A key concern for the UK and some other states is how much power these new groups will have over national spending priorities. The UK wants to ensure that no EU body can dictate how the Treasury spends money. This could make it hard for the new oversight groups to organise the bailout of a large bank operating across borders, a concern among EU policy makers since long before the recent financial crisis.

The UK and other countries that don't use the euro are also worried that the new big-picture regulatory group, which will be known as the European Systemic Risk Board, will give the European Central Bank, which manages the euro-zone economy, too much sway over their own economies.

Under the commission's plan, either the ECB president or another representative from a national regulatory authority could chair this new group.

A group headed by former International Monetary Fund Managing Director Jacques de Larosiere first suggested this new framework in February. There have been a series of negotiations between the commission and EU governments since then, though most of the commission's current proposal adheres to the de Larosiere group's original ideas. The commission plan still needs final approval from EU lawmakers and national governments, with further debates and negotiations likely in the coming months.